Speed reducer comprising two intermediate transmission lines

Abstract

The invention relates to a speed reducer having two intermediate transmission lines ( 4, 5 ) in particular for a turbine engine, comprising an input line ( 2 ) and an output line ( 3 ) driven by the input line by means of said intermediate lines, said intermediate lines being substantially in parallel with an axis (B) of rotation of the input line ( 2 ), said reducer further comprising means for distributing loads between the intermediate lines ( 4, 5 ), characterised in that said distribution means comprise a pinion ( 7 ) which is rigidly connected to a shaft ( 6 ) of the input line, the input line being movable in translation along said axis (B) and comprising two rings having helical external teeth ( 7 a, 7 b ), the helices of which are oriented in opposite directions, each cooperating respectively with a pinion ( 12, 13 ) of an intermediate line ( 4, 5 ). The invention also relates to a turbine engine comprising such a speed reducer and to a method for distributing the loads in such a reducer.

1 . Turbine engine comprising at least one speed reducer, said speed reducer having two intermediate transmission lines, in particular for a turbine engine, comprising an input line and an output line driven by the input line by means of said intermediate lines, said intermediate lines being substantially in parallel with an axis B of rotation of the input line, said speed reducer further comprising distributing loads means between the intermediate lines, wherein said distribution loads means comprise a pinion which is rigidly connected to a shaft of the input line, the input line being movable in translation along said axis and comprising two rings having helical external teeth, the helices of which are oriented in opposite directions, each cooperating respectively with a pinion of an intermediate line. 
     
     
         2 . Turbine engine according to  claim 1 , wherein said pinions connected to the intermediate lines are translationally fixed in parallel with the axis B. 
     
     
         3 . Turbine engine according to  claim 1 , wherein the two rings having helical external teeth have tilt angles of the helix which are substantially equal in absolute value. 
     
     
         4 . Turbine engine according to  claim 1 , wherein the two rings having helical external teeth have the same diameter. 
     
     
         5 . Turbine engine according to  claim 4 , wherein the two rings having helical external teeth are joined so as to form chevrons. 
     
     
         6 . Turbine engine according to  claim 1 , wherein the two rings having helical external teeth have substantially the same extension along the axis of rotation B. 
     
     
         7 . Turbine engine according to  claim 1 , wherein the helix of each ring having helical external teeth is designed in such a way that, during the transmission of a torque, an axial force is exerted on said ring by the pinion connected to the corresponding intermediate line, in the direction of the other ring having helical external teeth. 
     
     
         8 . (canceled) 
     
     
         9 . Method for transmitting a rotational torque, in a turbine engine, by means of a speed reducer comprising an input line, two intermediate transmission lines, and an output line driven by the input line by means of said intermediate lines, the intermediate lines being substantially in parallel with an axis B of rotation of the input line, the method consisting in adjusting the axial position of the input line, along said axis, so as to equalise the loads between the two intermediate lines. 
     
     
         10 . Method for transmitting a rotational torque according to  claim 9 , wherein the adjustment of the axial position of the input line is carried out automatically by the reducer and results from an equalisation of the torques transmitted by the input line to the intermediate lines respectively.